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MONITORIZACIN Y PERFUSIN RENALSANDRA MILENA DIAZ CASTRORI ANESTESIOLOGAUNIVERSIDAD MILITAR NUEVA GRANADAHOSPITAL UNIVERSITARIO CLINICA SAN RAFAELMONITORIZACINMedida es la determinacin de una cantidad fsica.Medimos cantidad de una sustancia (masa) y su estado de energa.Unidades: Forma especifica de medir una dimensin: longitud en m, tiempo en seg., masa en Kg, corriente en A, T en K, No. Molculas en moles.MONITORIZACINPeso: Fuerza de gravedad que acta sobre la masa de un cuerpo, se determina balanceando la fuerza del paciente sobre una masa conocida. Mtodo que se utiliza tambin para medir PVC.

When we measure the central venous pressure using a simple manometer, we are observing the balance of forces between the patient's venous pressure and the force of gravity acting on a fluid column ( Fig. 38-4 ). When the same pressure is measured electronically, we are balancing a Wheatstone bridge (a system of resistors used to determine an unknown resistance) ( Fig. 38-5 ).3MONITORIZACINMedicin PVC:

Puente de WheatstoneIf we were to insert a clear tube into the vein and hold the tube vertical with respect to gravity, we would observe the mass of blood in the tube raised a certain distance (centimeters) against the force of gravity by the central venous pressure until a balance point is reached. Energy is lost in the work done in raising the fluid column, distending the tubing, and frictional losses. The actual venous pressure is slightly greater than we can reasonably measure4MONITORIZACINMedicin PA:

These devices monitor the oscillating signal generated in the cuff by the arterial pressure changes. The cuff first inflates to above systolic pressure, at which point the signal and oscillations are abolished. Then the cuff slowly deflates in a stepwise fashion. The pressure at which the oscillating pressure signal first appears is interpreted as the systolic pressure. The signal increases in amplitude as the cuff pressure decreases. The point at which the signal is at maximal amplitude is interpreted as mean arterial pressure. As cuff pressure decreases further, the oscillations drop off rapidly. Diastolic pressure is mathematically inferred from the systolic and mean values5MONITORIZACINMedicin usando energa de sonido:1842: Doppler describe el cambio de los picos del sonido cuando la fuente del sonido se mueve.

Sound waves are small fluctuations in pressure, density, and velocity that can propagate through matter of any form: solid, liquid, or gas. In 1842, Doppler first described the apparent change in pitch of a sound that occurred when either the source of the sound or the listener was moving. The Doppler effect is used in echocardiography to determine the presence and degree of valvular regurgitation by converting the Doppler shift of sound waves reflected from erythrocytes into a color display (see Appendix 7 ; also see Chapter 41 ). Cardiac output also can be estimated from descending thoracic aortic blood velocity by using a Doppler technique. These devices estimate the blood flow in the descending aorta and ignore flow to the head and arms. They calibrate descending aortic flow to cardiac output by assuming a constant proportional relationship between the two flows.6MONITORIZACINMedicin usando energa elctrica:

Electric potentials on biologic surfaces are too small to observe directly and must be amplified and processed before display. ECG potentials on the skin are in the 1-mV range, and EEG potentials are near 0.1mV. illustrates why electric potentials on biologic surfaces are so small. The heart generates an electric signal as a result of the synchronous depolarization and repolarization of multiple cells. The electric potentials generated by the heart are measured between two skin electrodes, A and B. As the figure shows, there are multiple effective resistances and capacitances in the tissues between the EMF source and the measuring electrodes. These impedances reduce the magnitude of the voltage signal at the skin. The shunt resistors R3, R4, and R5 combined with the series resistors R1, R2, and R3 form what is called a voltage divider network. 7MONITORIZACINSe debe concentrar y amplificar la seal.

MONITORIZACINMedicin usando Ley Lambert y absorcin de la luz:

Conociendo la intensidad de la luz, que ilumina una cmara de dimensiones conocidas. La concentracin de una sustancia disuelta puede ser determinada si se mide la incidencia e intensidad de la luz.The relative absorption or reflection of light at different wavelengths is used in several monitoring devices to estimate the concentrations of dissolved substances (e.g., carbon dioxide in respiratory gas and hemoglobin in plasma). This type of measurement is called spectrophotometry and is based on the Beer-Lambert law of absorption, which states that if a known intensity of light illuminates a chamber of known dimensions, the concentration of a dissolved substance can be determined if the incident and transmitted light intensity is measured. 9MONITORIZACIN RENALInsuficiencia renal aguda: 5 30% en UCI, Mortalidad del 50 80%Complicacin severa en cx mayor (1 - 7%)Causa 60% de muerte en POP.Perioperatorio 50% requieren dilisis.Causas perioperatorias: Isquemia, nefropata por medio de contraste, aminoglucosidos, norepinefrina, embolismo graso, sepsis.

Evidence continues to grow supporting the idea that postoperative AKI is a mosaic of several pure nephropathies, each of varying importance for a particular patient and procedure, suggesting that only individualized renoprotection strategies, guided by timely point-of-care renal function monitoring, will be helpful in developing effective renoprotection strategies.10MONITORIZACIN RENALFactores de riesgo IRA en POP:

Sndrome metablico, HTA, Enfermedad coronaria, DM, Enfermedades primarias del rin.

Estados de bajo gasto, uso medios de contraste, sepsis, uso de inotrpicos, uso de baln de contrapulsacin artico, ictericia, trasfusiones.11FISIOPATOLOGIA IRA

Mechanism for renal sodium and volume regulation in response to decreased extracellular volume (e.g., hypovolemia, hemorrhage). ANF, atrial natriuretic factor; B.P., blood pressure; C.O., cardiac output; GFR, glomerular filtration rate; NaCl, sodium chloride. 12FISIOPATOLOGIA IRAMONITORIZACIN RENALOliguria (< 0.5 ml/kg/hora) cambia en perioperatorio:

Anestesia: TA y GC Flujo sanguneo renal Filtracin glomerular y Volumen urinario. Volumen urinario: Premedicacin con narcticos, barbitricos, estrs Qx: Catecolaminas, ADH.Bloqueo espinal: estimulo simptico As previously discussed, a monitor of balanced supply/demand of regional renal perfusion, particularly in the renal medulla, would be an ideal, although currently unavailable, direct monitoring tool. The best tools currently available intraoperatively are indirect hemodynamic monitors that can assist in optimizing conditions consistent with kidney well-being, such as ensuring adequate intravascular volume (i.e., preload), cardiac performance, and systemic perfusion. Serum chemistries and urinary indices may enable the assessment of adequate distribution of cardiac output to the kidneys themselves.14MONITORIZACIN RENALMarcadores indirectos de perfusin renal:Entrega de oxgeno: Gases arteriales y hematocritoPO2: Flujo sanguneo renal y vasoconstriccin,PCO2: Flujo sanguneo renal.Hcto < 22% se asocia 2 3 veces ms riesgo de dilisis en POP.15MONITORIZACIN RENALMarcadores indirectos de perfusin renal:Perfusin sistmica: PAS y presin de pulso.TAS > 160 mmHg y pp > 40 mmHg: riesgo de IRA y dilisis en POP.Volumen intravascular:Presin aurcula izquierda: PAI produce flujo sanguneo renal por estimulo del PNA (dilatacin arteriola aferente y vasoconstriccin eferente).16MONITORIZACIN RENALMarcadores indirectos de perfusin renal:Volumen intravascular: PVC, POAP, Volumen fin distole.A quin?: Depende de reserva cardiaca funcional y grado de lesin intraoperatorio esperado. rea de fin de distole VI: Ecocardiograma transesofagico.17MONITORIZACIN RENALMarcadores indirectos de perfusin renal:Flujo sanguneo: EKGDoppler arterias renalesEcocardiograma transesofagico.The electrocardiogram is essential to detect the depolarization-repolarization changes consistent with the electrolyte abnormalities of renal dysfunction and to monitor for normal rate and rhythm. The synchronized atrial kick preceding ventricular contraction may contribute significantly to cardiac output in the patient with a noncompliant left ventricle. Transesophageal echocardiography 2D and renal arterial Doppler waveform images, primarily of the left kidney, can be used to assess changes in pulsatility and resistive indices and qualitatively describe RBF changes over time18MONITORIZACIN RENALBiomarcadores tradicionales IRA:Volumen urinarioOsmolalidad urinariaCreatinina srica y BUNSodio urinario, FeNaDepuracin creatinina: Ecuacin de Cockroft-GaultEstas herramientas proveen un diagnostico tardio de IRA,19MONITORIZACIN RENALVolumen urinario:Implica flujo sanguneo renalOliguria prolongada es predictor o diagnostico de Insuficiencia renal aguda. (0.5 cc/kg/hora).400 500ml mnimo se requiere para filtrar los residuos nitrogenados diarios.Osmolalidad urinaria > 500mOsm, VPP 60 100% en IRA prerrenal y < 350mOsm, VPP 69 95%. Osmolaridad urinaria: [(Na+ + K+) x 2] + (Urea/5.6)20MONITORIZACIN RENALCreatinina srica:No tiene una realizacin lineal con los cambios en la funcin renal.Se modifica con TMT sulfa, N - acetil cistena.Difiere segn masa muscular, gnero, edad.

21MONITORIZACIN RENALBUN: con ingesta de protenas y metabolismo aumentado (sepsis, trauma). Disfuncin heptica.60% es reabsorbida si flujo urinario es bajo y 40% si es alto.22MONITORIZACIN RENALSodio urinario y FeNa:[(Na+ urinario x creatinina srica) / (Na+ serico x creatinina urinaria)] x 100Dx en necrosis tubular aguda si > 1%.Na urinario < 20 meq IRA prerrenal y > 40 meq Necrosis tubular aguda.Na urinario es inespecfico (segn volumen).23MONITORIZACIN RENALDepuracin de creatinina:Filtracin glomerular depende de (GRF): Coeficiente de filtracin glomerular (Kf)Presin capilar glomerular (PGC)Presin en la capsula de Bowman (PBC)Presin onctica del plasma (PPO)

GRF = Kf x (PGC PBC PPO)24MONITORIZACIN RENALFlujo sanguneo renal:FSR = FPR / 1 - HctoFPR = UV / (A RV)U = Concentracin urinaria del marcadorV = Volumen urinarioA = Concentracin plasmtica del marcadorRV = Concentracin renal de plasma venoso25MONITORIZACIN RENALDepuracin de creatinina:Volumen de plasma que el rin puede aclarar de creatinina en un minuto.Error en calculo varia del 10 27% segn: peso, orina recolectada, rea de superficie corporal.Ecuacin de Cockroft-Gault:(140 - Edad) x (Peso en Kg)/ (72 x Creatinina srica)26MONITORIZACIN RENALFlujo sanguneo renal: (medicin)Indocianina verde por termorregulacinMedicin PO2 tisular con electrodos multihiloAclaramiento con krypton-85 y xenon-133Renograma y transito de trazador radioactivo filmado mediante cmara gammaDoppler arterias renalesEcocardiografa transesofagica intraoperatoria.27MONITORIZACIN RENALPropiedades ideales de biomarcadores de IRA No invasivos y fciles de realizarAlta sensibilidadAlta especificidad para IRAIdentifique la localizacin de la lesin primariaEstratificacin de riesgo y pronosticoMonitorizar respuesta al tratamiento.28MONITORIZACIN RENALBiomarcadores tempranos de IRA Filtracin glomerular:Cistatina CPptido natriurtico proatrialTriptfanoRespuesta al estrsIL 18 urinaria.Factor activador de plaquetasLipocalina asociada a gelatinasa de neutrfilos

29MONITORIZACIN RENALBiomarcadores tempranos de IRA Cistatina C: Cistena inhibidor de proteasa, sintetizada por clulas nucleadas sanguneas.No se afecta por edad, genero o masa muscular. 50% en niveles sricos predice IRA 48 horas antes que creatinina se ,30MONITORIZACIN RENALBiomarcadores tempranos de IRA IL 18 urinaria:Citoquina proinflamatoria inducida en tbulo proximal Sensibilidad y especificidad del 90%4 6 horas postqx.Niveles > 100 pg/mg predicen IRA 24 horas antes que creatinina.

31MONITORIZACIN RENALBiomarcadores tempranos de IRA Lipocalina asociada a gelatinasa de neutrfilos Protena de 24 kdExpresin solo en caso de lesin epitelial, con de 10 veces en plasma y 100 veces en orina; 2 6 horas posterior a Cx.

32MONITORIZACIN RENAL

(neutrophil gelatinase-associated lipocalin) platelet-activating factor and urinary sodium hydrogen exchanger isoform-333MONITORIZACIN RENALDao tubular renal:Ag epitelial tubular proximalFosfatasa alcalinaGlutamil transpeptidasaALA amino peptidasaGlutation trasnferasaDisfuncin tubularMicroglobulinaAlbuminaADAAg epitelial tubular 1Lisosima y ribonucleasaCeruloplasmina34EL MONITOR PICCOPulse-induced Contour Cardiac Output

El monitor PICCO utiliza parametros dinamicos para predecir la respuesta a la infusin de lquidos y el estado fisiologico del paciente.35EL MONITOR PICCOEvala la respuesta a la infusin de lquidos: PPV (variacin de la presin de pulso) y SVV (variacin en el volumen latido)Medicin Gasto cardiaco: Termodilucin transpulmonar, anlisis del contorno del pulso arterialContenido de agua extravascular en los pulmones (EVLW)Volumen global de fin de distole (GEDV)Fraccin de eyeccin global.

El monitor PICCO utiliza parmetros dinmicos para predecir la respuesta a la infusin de lquidos y el estado fisiologico del paciente.36EL MONITOR PICCOPPV (variacin de la presin de pulso)

The arterial pulse pressurethe difference between the systolic and the diastolic pressureis directly proportional to stroke volume and inversely related to arterial compliance. 37EL MONITOR PICCOEvala la respuesta a la infusin de lquidos: SVV (variacin en el volumen latido)

. SVV is determined by analysis of the continuous arterial pulsecontour. This method uses the area under the systolic portion of thearterial pressure curve for beat-to-beat determination of stroke volume (inrelative values) and their variation over the respiratory cycle. Its feasibilityand appropriateness in estimating cardiac preload and volume responsivenesshas been reported in several clinical trials. An SVV of 10% is considered as a cutoff discriminating betweenfluid responders and nonresponders; if SVV is less than 10% COwill not increase in response to volume loading and thus may be avoidedas a therapeutic challenge. SVV is now accepted as an indexof fluid responsiveness and was validated in ventilated postcardiacpatients,21,23,24 in the operating room during neurosurgery20 and inseptic shock patients.38EL MONITOR PICCOSVV: depende de la fase en la curva de Frank- Starling, se encuentra la funcin cardiaca del paciente. (< 10% no rta)

. 39EL MONITOR PICCOGasto Cardiaco: Termodilucin transpulmonarSe mide en la punta del catter arterial PICCO, las variaciones de T en direccin opuesta a la corriente.

Para determinar el volumen del gasto cardiaco se precisa una inyeccion en una vena central de un bolo de(solucion salina isotonica). Despues de inyectar este indicador y pasar al sistema cardiopulmonar, el termistormide en la punta del cateter arterial PiCCO las variaciones de temperatura en direccion opuesta a la corriente. El volumen del gasto cardaco se calcula mediante la ecuacion Steward-Hamilton de la superficie bajo lacurva de termodilucion transpulmonar. Del periodo medio de paso (MTt) y el tiempo de descenso (DSt)de la curva de termodilucion se determinan volumen de precarga y agua pulmonar. En un Shunt intracardiacoizquierda derecha, se registran y valoran por separado las curvas de termodilucion del Shunt y la circulacionsanguinea fisiologica.40EL MONITOR PICCOGasto Cardiaco: Termodilucin transpulmonarSe calcula mediante la ecuacin Steward-Hamilton:

Para determinar el volumen del gasto cardiaco se precisa una inyeccion en una vena central de un bolo de(solucion salina isotonica). Despues de inyectar este indicador y pasar al sistema cardiopulmonar, el termistormide en la punta del cateter arterial PiCCO las variaciones de temperatura en direccion opuesta a la corriente. El volumen del gasto cardaco se calcula mediante la ecuacion Steward-Hamilton de la superficie bajo lacurva de termodilucion transpulmonar. Del periodo medio de paso (MTt) y el tiempo de descenso (DSt)de la curva de termodilucion se determinan volumen de precarga y agua pulmonar. En un Shunt intracardiacoizquierda derecha, se registran y valoran por separado las curvas de termodilucion del Shunt y la circulacionsanguinea fisiologica.41EL MONITOR PICCOGasto Cardiaco: Evaluacin contorno pulso arterial.Wesseling y colaboradores 1974Determinado por la compliance aortica. GC = Volumen sistlico x FCVS = rea bajo la curva porcin PAS/compliance aorticaCompliance aortica: volumen sistlico no calibrado basado en el contorno del pulso/volumen sistlico por termodilucin

LV stroke volume is computed by dividing the measured area under the systolic portion of the arterial pressurewaveform by the aortic impedance. A subsequent multiplication by the heart rate yields pulse-contour CO. To adjust for aortic impedance,which differs from patient to patient, the PiCCO monitor uses the thermodilution measurement of CO for the calibration of the system.The calculation is as follows: CO/heartrate Asys=Zao, where Zao=SVpc/SVtdAsys, area under systolic pressure waveform; Zao, aortic impedance;SVpc, uncalibrated stroke volume based on pulse-contour; and SVtd,stroke volume by thermodilution.The volume change and subsequentpressure change is described as the compliance function of the aorta.42EL MONITOR PICCOGasto Cardiaco: Evaluacin contorno pulso arterial.

Figure 8. Top, A diagram showing the themodilution cardiac output measurement as a referencefor the continuous pulse contour cardiac output measurement. Bottom, The PiCCO monitor pulsecontour cardiac output analysis algorithm, which incorporates the aortic compliance, the area underthe systolic portion of the arterial waveform, a patient-specific calibration factor based on thethermodilution measurement of cardiac output, and the shape of the pressure curve.43EL MONITOR PICCOContenido de agua extravascular en los pulmones (EVLW)Marcador de severidad de la lesin pulmonarDeteccin por termodilucin: Pearce and Beazell.

cuantifica el liquido estancado fuera de los capilares pulmonares enel parenquima pulmonar. Engloba el agua pulmonar total intersticial, intraalveolar e intercelular en todas lasareas pulmonares perfundidas. El derrame pleural no artefacta el valor, dado que no recibe perfusion alguna44EL MONITOR PICCO Contenido de agua extravascular en los pulmones ITTV = GC x MTt froPTV = GC x DSt fro

GEDV = ITTV PTVITBV = 1,25 x GEDV

EVLW = ITTV - ITBV

ITTV = Volumen trmico intratoracicoMTt fro = Tiempo medio de transito del inyectable fro.PTV: Volumen termico pulmonarDSt fro: Tiempo al final de la pendiente del inyectable froGEDV: Volumen de fin de diastoleITBV: Volumen intratoracicoEVLW: Contenido de agua extravascular en los pulmones (alveolar + intersticial)45Limitaciones del mtodo de dilucin:

Obstruccin Vascular (TEP).PEEP: redistribucin del flujo pulmonar y PVC.Lesin pulmonar focal.Lobectoma: ITBV no corresponde a 1.25 x GEDV.EL MONITOR PICCOEffect of PEEP The effect of PEEP on EVLW measurement is stillcontroversial since the use of high levels of PEEP could potentially leadto pulmonary vascular defect. This may explain the observation by someexperimental studies a decrease in EVLWmeasured by dilution techniquesduring PEEP application.91 In contrast, PEEP may induce a redistribution of pulmonary blood flow toward previously excluded areas and henceartificially increase EVLW by recruiting the lungs.87,92 It is important toappreciate that in addition to potentially affecting measurement of EVLWby dilution method, PEEP may also have an effect on the real amount ofEVLW; in case of elevated pulmonary capillary pressure due to LV dysfunction,the application of PEEP may decrease EVLW by decreasingpulmonary capillary pressure.93,94 In contrast, PEEP may increase EVLWby increasing central venous pressure leading to reduced lymph flow fromthe lungs (and thus lymphatic congestion), and by increasing lung volumeleading to vascular congestion and edema.95 In summary, one must keep inmind that PEEP may affect both the amount and the measurement ofEVLW by dilution methods. Finally, a recent study showed that despitethese concerns, compared with quantitative computed tomography scan (atechnique not affected by perfusion defects), dilution methods are veryaccurate in assessment of EVLWin patients with ARDS ventilated with highlevels of PEEP (10 to 20 cm H2O).46Aplicaciones clnicas EDLW:

Pronostico: > 15 ml/kg 65% mortalidad< 10 ml/kg 33% mortalidadDiagnostico: Valor normal: 3 7 ml/kg Edema pulmonar (mejor rendimiento que Rx trax y diagnostico diferencial: Hidrosttico vs permeabilidad)Tratamiento: Terapia de fluidos dirigida.EL MONITOR PICCO47Fraccin de eyeccin global:EL MONITOR PICCO

48MEDIDA FLUJO SANGUNEO RENALcido paraaminohiprico: gold estndarPhase contrast-cine-MRIAngiorresonancia 3D con gadolinioEcografa con contraste y seal aumentadaDoppler de arterias renalesTomografa por emisin de positronesisotopic inert gasestransrenal dye dilution with indocyanine greenDirect flow meters

49MEDIDA FLUJO SANGUNEO RENALEcocardiograma transesofagico:Evala llenado ventricular: Terapia de fluidos dirigida, incluidos pacientes con hipertrofia VI.FEVI < 55% Presin auricular > 15 mmHgEste parmetro se altera en insuficiencia mitral, FA, bajo gasto.Estimacin GC a travs volumen sistlico.Evaluacin funcin ventricular:FAC = (EDA ESA) / EDAFractional area change (FAC) during systole is a commonly used measure of global LV function. It is measured by using the simple formula (EDA - ESA)/EDA, where EDA is the cross-sectional area at end diastole and ESA is the cross-sectional area at end systole. Marked changes in FAC are apparent by simply viewing the real-time images50MEDIDA FLUJO SANGUNEO RENALcido paraaminohiprico:Se secreta en clulas tbulo proximal por un transportador de aniones.Requiere 4 muestras de intervalos cada 45 minCalculo: CPAH = PAH urinario x vol urinario / PAH plasmaRBFPAH = 1.1 (FSR / 1 Hcto)FSR = CPAH

MEDIDA FLUJO SANGUNEO RENALPhase contrast-cine-MRIMide el movimiento de protones a travs de gradientes en un campo magntico, que adquieren un cambio de fase proporcional a la velocidad.Cine-MRI, toma datos del ciclo cardiaco, EKG, y produce imgenes de algunos intervalos que combinado con contraste, calcula flujo sanguneo . (Producto de la velocidad media por el rea del vaso).Geraldine Corrigan et al. PAH extraction and estimation of plasma flow in human postischemic acute renal failure. Am J Physiol Renal Physiol 277:F312-F318, 1999.It depends on the use of magnetic field gradients toacquire velocity information from phase data. As the precessingprotons move in the presence of a magnetic field gradient,they acquire a phase shift that is proportional to velocity.Images encoding the phase information are called phasecontrast-MRI. Cine-MRI is a technique that acquires datathroughout the cardiac cycle and uses a simultaneouslymonitored electrocardiogram to produce images at selectedintervals. When the cine-MRI technique is combined withphase contrast to produce images that portray the spatialdistribution of velocities during the cardiac cycle, the techniqueis known as phase contrast-cine-MRI. If the phasecontrast acquisition is encoded for motion through the imagingplane, the product of the average velocity in a regionencompassing a blood vessel and the vessel area yields theflow rate52MEDIDA FLUJO SANGUNEO RENALDoppler arterias renales:Mide la velocidad y direccin de los eritrocitos que se procesan y se grafican en curva frecuencia vs tiempo.Flujo de alta velocidad por estenosis arterial.

Angiorresonancia 3D con gadolinio.Estenosis de arterias renales: S 91 94% y E 90%RAM: Fibrosis sistmica nefrogenica.MEDIDA FLUJO SANGUNEO RENALAngiorresonancia 3D con gadolinio:Modelo de dos compartimentos:Concentracin de Gadolinio queladoIntensidad de la seal de RM: (St S0)/S0

Diego R. Martin et al. Individual Kidney Blood Flow Measured with Contrast- enhanced First-Pass Perfusion MR Imaging. Radiology: Volume 246: Number 1, January 2008.Gadolinium chelate phantom imaging.Since the two-compartmentmodel assumes a linear relationship betweengadolinium chelate concentrationand MR signal intensity (SI), the SI behaviorof the renal perfusion imagingsequence was assessed with 17 gadoliniumchelatedoped plasma phantoms.Freshly frozen human plasma was obtainedfrom the hematology division atEmory University Hospital (Atlanta,Ga). The phantoms were prepared individuallyin 50-mL plastic screw-capsealed tubes with gadolinium chelate(gadopentetate dimeglumine, Magnev-ist; Berlex Laboratories, Wayne, NJ)concentrations varying from 0 to 30mmol/L. Within 2 days of preparation,the phantoms were arranged on a styrofoamholder and imaged at room temperatureby using a 3D spoiled gradientechoMR imager with sequence parametersreproducing those used for in vivorenal perfusion imaging (see Single-Kidney RBF-Gadoliniumenhanced RenalPerfusion Imaging).

Primero se toman imgenes en resonancia que involucren los dos parenquimas renales por completo. Posteriormente se inyecta el medio de contraste (gadolineo).

Relative SI values were determinedby using the formula (St S0)/S0,where St is the signal at time t and S0 isthe mean unenhanced signal, calculatedfrom the mean of at least three unenhancedimages. Evala el rea transversal de la arteria renal en cada imagen y calcula el FSR, con el producto de la velocidad promedio por el rea.54MEDIDA FLUJO SANGUNEO RENALAngiorresonancia 3D con gadolinio:Integral de Kety-Schmidt: La tasa de absorcin de un indicador es igual al flujo de sangre a travs del rgano, multiplicado por la diferencia arteriovenosa del indicador.

Ct: Concentracin de gadolinio totalV: Volumen renalF: FSRCa: Concentracin de gadolinio en arteria renaltd: tiempo en el que el gadolinio se mide.

Diego R. Martin et al. Individual Kidney Blood Flow Measured with Contrast- enhanced First-Pass Perfusion MR Imaging. Radiology: Volume 246: Number 1, January 2008.Gadolinium chelate phantom imaging.Since the two-compartmentmodel assumes a linear relationship betweengadolinium chelate concentrationand MR signal intensity (SI), the SI behaviorof the renal perfusion imagingsequence was assessed with 17 gadoliniumchelatedoped plasma phantoms.Freshly frozen human plasma was obtainedfrom the hematology division atEmory University Hospital (Atlanta,Ga). The phantoms were prepared individuallyin 50-mL plastic screw-capsealed tubes with gadolinium chelate(gadopentetate dimeglumine, Magnev-ist; Berlex Laboratories, Wayne, NJ)concentrations varying from 0 to 30mmol/L. Within 2 days of preparation,the phantoms were arranged on a styrofoamholder and imaged at room temperatureby using a 3D spoiled gradientechoMR imager with sequence parametersreproducing those used for in vivorenal perfusion imaging (see Single-Kidney RBF-Gadoliniumenhanced RenalPerfusion Imaging).

Primero se toman imgenes en resonancia que involucren los dos parenquimas renales por completo. Posteriormente se inyecta el medio de contraste (gadolineo).

Relative SI values were determinedby using the formula (St S0)/S0,where St is the signal at time t and S0 isthe mean unenhanced signal, calculatedfrom the mean of at least three unenhancedimages. Evala el rea transversal de la arteria renal en cada imagen y calcula el FSR, con el producto de la velocidad promedio por el rea.55MEDIDA FLUJO SANGUNEO RENALEcografa con contraste y seal aumentada:Infusin de un medio de contraste a travs de microburbujas de gas. Mide la velocidad a la que estas microburbujas reabastecen el tejido; y la seal cuando el tejido esta completamente lleno por estas nos da el volumen sanguneo tisular total.Software: QLAB.Kambiz Kalantarinia. Real-time measurement of renal blood flow in healthy subjects using contrast-enhanced ultrasound. Am J Physiol Renal Physiol. 2009 October; 297(4): F1129F1134.Ecografa con contraste: Se inyectan unas microburbujas de gas para aumentar la imagen del ultrasonido, luego se mide la velocidad a las que estas microburbujas reabastecen el tejido despus de su destruccin y as se evalua el flujo sanguneo. Los datos se obtienen mediante un software: QLAB. Cuando el tejido esta lleno de estas microburbujas, el signo de estas sugiere el volumen sanguneo total tisular; el producto de este volumen sanguneo por la velocidad del flujo sanguneo, nos da el flujo sanguneo tisular.

56MEDIDA FLUJO SANGUNEO RENALEcografa con contraste y seal aumentada:

Kambiz Kalantarinia. Real-time measurement of renal blood flow in healthy subjects using contrast-enhanced ultrasound. Am J Physiol Renal Physiol. 2009 October; 297(4): F1129F1134.Corteza renal: zona de mayor ecogenicidad entre la capsula y la medula.Piramides: zonas mas oscuras y profundas que se completan ms lentamente con las microburbujas

57MEDIDA FLUJO SANGUNEO RENALEcografa con contraste y seal aumentada:

Kambiz Kalantarinia. Real-time measurement of renal blood flow in healthy subjects using contrast-enhanced ultrasound. Am J Physiol Renal Physiol. 2009 October; 297(4): F1129F1134.Fig. 2.Graphic depiction of changes in acoustic intensity vs. time after destruction of microbubbles in the tissue with high-energy ultrasound wave.58MEDIDA FLUJO SANGUNEO RENALDoppler de arterias renales:Arteria renal derecha: Relacin con tronco celiaco y arteria mesentrica superior.Mide el pico sistlico y diastlico de la onda de pulso arterial.Calcula la velocidad media: PDV+ 1/3 (PSV PDV)

Kambiz Kalantarinia. Real-time measurement of renal blood flow in healthy subjects using contrast-enhanced ultrasound. Am J Physiol Renal Physiol. 2009 October; 297(4): F1129F1134.The right renal artery was identified using color Doppler from the anterior approach by its relationship to the celiac axis and superior mesenteric artery. The right renal artery ostium was insonated at 1.6 MHz with a pulsed Doppler gate set at 7.5 mm and Doppler angle correction set at 60. The angle correction curser was positioned parallel to the renal artery walls, obtaining velocities comparable to accepted diagnostic renal artery velocity criteria. Once three consistent Doppler waveforms were presented on-screen, the peak systolic and diastolic velocities (PSV and PDV) of one of the waveforms were measured using on-screen calipers. These measurements were taken in the same fashion pre- and postprandial. Mean Doppler velocities were calculated by the following formula: mean velocity = PDV+ 1/3 (PSV PDV)59MEDIDA FLUJO SANGUNEO RENALTomografa por emisin de positrones:Se basa en detectar y analizar la distribucin tridimensional que adopta en el interior del cuerpo un radiofrmaco de vida media ultracorta Utiliza: Agua marcada 15 (H2O 15), T1/2 = 2 min.Amonio marcado (NH3), T1/2 = 11 min.Cintica H2O, modelo monocompartimental para altos flujos sanguneos.Dynamic renal blood flow measurement by positron emission tomography in patients with CRF. Am J Kidney Dis. 2002 Nov;40(5):947-54.GRACIAS!!